Muffler



E. H BOBO Feb. 5, 1935.

MUFFLER Original Filed Sept. 10, 1931 2 Sheeis-Sheet 1 31 my: u i L EZZB0ZOE 19% cos fluonwt a.

E. H. BOBO Feb. 5, 1935.

MUFFLER 1931 2 Sheets-Sheet 2 Original Filed Sept. 10

Patented Feb. 5, 1935 UNITED STATES MUFFLER Edward H. Bobo, Ranger, Tex, lllsignor of onehalf Susan Hunt, Banger, Tex.

Application September 10, 1931, Serial No. 562,174 Renewed April 23, 1934 QCIlims.

The invention relates to mufllers for internal combustion engines, primarily those of aircraft, and it aims to provide an exceptionallysimple and inexpensive construction, yet one which will be unusually efllcient to silence the exhaust without creating an appreciable amount of back pressure against the pistons of the motor.

With the foregoing in view, the invention resides in the novel subject matter hereinafter dem scribed and claimed, description being accomplished by reference to the accompanying drawings.

Fig. 1 is a side elevation showing one form of muiller constructed in accordance with the invention.

Fig. 2 is a central longitudinal sectional view through the muiiier shown in Fig. 1.

Figs. 3 and 4 are transverse sectional views on lines 33- and 4-4 of Fig. 2.

Fig. 5 is a longitudinal sectional view showing a slightly difierent form of construction.

Fig. 6 is a transverse sectional view on line 66 of Fig. 5.

Fig. 7 is a side elevation partly in section showing a still further variation.

. Fig. 8 is a transverse sectional view on line 8-8 of Fig. 7.

In the drawings above briefly described, the

numeral 10 denotes an elongated tubular casing 30 whose front end 11 is provided with a gas inlet 12, the rear end 13 of said casing being entirely open in all forms of construction herein disclosed, although when using the structure of Fig. 5, said rear end could well be closed. A longitudinal gas discharge slot 14 is formed in the casing 110 and extends substantially from end to end thereof, and I provide a series of gas deflecting plates within the casing for directing the exhaust gases through said slot. These deflecting plates are 40 denoted at 15 in the constructions shown in Figs. 1 to 4, and in Fig. 8, and are indicated at 15 in Figs. 5 and 6.

The plates 15 or 15' are spaced apart longitudinally of the casing 10 and are each provided with an arcuate edge 16 (Fig. 8) secured against thewall of said casing by welding or in other desired way, and said curved edges of said plates are preferably provided either with relatively short outwardly projecting lugs 17 (Figs. 2 and 4) or 17' (Figs. 5 and 6), said lugs being received in the slot 14 and welded or otherwise secured to the longitudinal edges of the latter. The gas-intercepting sides of the deflector plates 15 and 15' are all disposed at acute angles to the wall of the casing 10 and the free edges 18 of said plates all curve toward the gas inlet 12. In the form of construction shown in Figs. 1 to 4, the deflector plates 15 gradually increase in width away from the gas inlet 12 until said width substantially equals half the diameter of the casing 10, and the remainder '5 of the plates 15 are of the latter width. In the construction shown in Figs. 5 and 6 however, the deflector plates 15' gradually increase in width away from the gas inlet 12 until the last of said plates extendscompletely across the interior of the casing 10. In either instance, the deflector plates serve to direct the exhaust gases with little retardation, through the discharge slot 14. When the plates 15 are of substantially the widths shown in Fig. 2, I provide a butterfly valve 19 in the open rear end of the casing 10, so that by properly positioning this valve, any desired amount of the exhaust gases may be allowed to directly escape through the open rear end 13 of the casing, the other gases passing on out through the slot 14.

In Figs. 1 to 4, an elongated transversely curved hood 20 is spaced .outwardly from the slotted side of the casing 10 and co-operates therewith in forming a crescent-shaped expansion chamber 21'which receives the exhaust gases from the slot 14. The hood 20 is provided with walls 22 secured to the casing 10, but the longitudinal edges 23 of said hood are spaced outwardly from said casing, sufliciently to provide outlet slots 24 for the exhaust gases, said edges 23 being preferably curved away from the casing 10, as shown.

The hood 20 co-acts with the casing 10 in forming opposed wallswhich provide two longitudinally extending air-conducting nozzles, said nozzles having transversely flared discharge por tions (between the casing 10 and the curved edges 23) through which the gases issue unretarded into the atmosphere.

In Figs. 5 and 6, two longitudinal flanges 25 are secured to the casing 10 along the longitudinal edges of the slot 14, said flanges projecting outwardly and being free of connection at their front and rear ends. These flanges are secured to the lugs 17' and hence are efl'ectively braced by the latter, and said lugs assist materially in properly anchoring the deflector plates 15. The longitudinal edges 26 of the flanges 25, preferably curve away from each other as illustrated more particularly in Fig. 6. The opposed walls or flanges 25 and their curved edges 26 provide a longitudinally extending gas-conducting nozzle having a transversely flared discharge portion (between the curved edges 26) through which the gases issue unretarded into the atmosphere.

In Figs. 7 and a, the hood 20' isidentical with the hood 20, except that it is transversely corrugated from edge to edge, and any desired number of the corrugations 27 may be secured to the casing 10, so that a multiplicity of separate outlets 24' are provided for the exhaust gases.

Like the form of construction first described, that shown in Figs. '7 and 8, provides two longitudinal gas-conducting nozzles having transversely flared discharge portions through which the'gases issue unretarded into the atmosphere.

Any form of the invention is comparatively simple and inexpensive, may be easily manufactured and installed, and will be eflicient to silence the motor to the required degree, without creating excessive back pressure. The device is well adapted to stream-line shaping for use upon aircraft to minimize resistance and may obviously be constructed of any desired length and in either unitary or sectional form.

The details disclosed may be considered as preferred, but within the scope oi the invention as claimed, numerous variations may be made.

I claim:---

1. A mufller comprising an elongated tubular casing having a-gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, and a plurality of transverse deflector plates in said casing and spanning said slot, each of said deflector plates having an arcuate edge and anotheredge extending from one end of said arcuate edge tothe other end thereof, said arcuate edge being secured against the wall of said casing and said other edge extending entirely across the interior of said casing, said deflector plates'being spaced apart longitudinally of said casing, having their gas-intercepting sides at acute angles to the slotted side of said casing, and having said other edges curved toward said inlet.

2. A mufller comprising an elongated tubular casing having a gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, and a plurality of transverse deflector plates in said casing and spanning said slot, each of 7 said deflector plates having an arcuate edge and another edge extending from one end of said arcuate edge to the other end thereof, said arcuate edge being secured against the wall of said casing and said other edge extending entirely across the interior of said casing, said deflector plates being spaced apart longitudinally of said casing, having their gas-intercepting sides at acute angles to the slotted side of said casing and having said other edges curved toward said inlet, said deflector plates being successively increased in width away from said inlet.

3. A mufller comprising an elongated tubular casing having a gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, and a plurality of transverse deflector plates in said casing and spanning said slot, each of said deflector plates having an arcuate edge and another edge extending from one end of said arcuate edge to the other end thereof, said arcuate edge being secured against the wall of said casing and said other edge extending entirely across the interior of said casing, said deflector plates being spaced apart longitudinally of said casing, having their gas-intercepting sides at acute angles to the slotted side of said casing and having said other edges curved toward said inlet, said arcuate edges of said'deflector plates having lugs secured in said slot.

4. A mufller comprising an elongated tubular casing having a gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, a plurality of transverse deflector plates in said casing and spanning said slot, each oisaid deflector plates having an arcuate edge secured against the wall of said casing, said deflector plates being spaced apart longitudinally of said casing, having their gas-intercepting sides at acute angles to the slotted side of said casing and having free edges curved toward said inlet, and a transversely arcuate hood spaced outwardlyfrom the slotted side of said casing-and forming therewith an elongated expansion chamber of crescent shape in transverse section, said hood having end walls secured to said casing, the longitudinal edges of said hood being free and spaced sufliciently from the casing to allow escape of gases. 1

5. A muiller comprising an elongated tubular casing having a gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, a plurality of transverse deflector plates in said casing and spanning said slot, each of said deflector plates having an arcuate edge secured against the wall of said casing, said deflector plates being spaced apart longitudinally of said casing, having their gas-intercepting sides at acute angles to the slotted side of said casing and having free edges curved toward said inlet, and a transversely arcuate hood spaced outwardly from the slotted side of said casing and forming therewith an elongated expansion chamber of crescent shape in transverse section, said hood having end walls secured to said casing, the longitudinal edges of said hood being free and spaced suflicientiy from the casing to allow escape of gases, said hood being transversely corrugated from edge to edge and having a number of its corrugations secured to said casing.

6. A muflier comprising an elongated tubular casing having a gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, a plurality of transverse deflector plates in said casing and spanning said slot, each of said deflector plates having an arcuate edge secured against the wall of said casing, said deflector plates being spaced apart longitudinally oi said casing, having their gas-intercepting sides at acute angles to the slotted side of said casing and having free edges curved toward said inlet, and two longitudinal flanges projecting outwardly from the longitudinal edges of said slot, said flanges having free outer edges, said arcuate edges of said deflector plates having lugs projecting through said slot and secured against the inner sides of said flanges.

7. A mufller comprising an elongated tubular casing having a gas inlet at one end, said casing being provided with a longitudinal gas discharge slot, a plurality of transverse deflector plates in said casing and spanning said slot, each or said deflector plates having an arcuate edge and another edge extending irom one end of said arcuate edge to the other end thereof, said arcuate edge being secured against the wall 01 said casing and said other edge extending entirely across the interior or said casing, said deflector plates being spaced apart longitudinally of said casing and having their gas intercepting sides at acute angles to the slotted side of said casing, and two longitudinal flanges projecting outwardlyirom the longitudinal edges 01 said slot and having free outer edges.

8. A structure as specified in claim "I; said flanges being transversely curved away from each other.

9. A nufller comprising an elongated tubular casing having a gas inlet at one end and a longitudinal gas discharge slot in one side, a plurality of transverse deflector plates spaced apart longitudinally of said tubular casing and secured therein, all or said deflector plates completely spanning the interior of the casing and said gas discharge slot, said deflector plates being increased gradually in width away from said gas inlet and being all disposed at an acute angle 

